Various systems have been proposed for water-going vessels in which one or more propellers are disposed beneath the waterline of the vessel for semi-submersible vessels or disposed within a portion of the hull of submersible vessels. Typically, the propellers in submersible vessels have been driven by diesel power, steam turbines or electric motors mounted within the hull of a vessel. A propeller shaft extends through the hull to the propeller mounted on the shaft outside the hull. Such systems have the disadvantages of shaft vibration and noise radiating from the shaft. Further, a rotating seal is necessary where the shaft passes through the hull but this is prone to leak. Alternative systems have been suggested using shaftless electric motors mounted outside of the hull with only electric power cables passing through the hull, as shown for instance in U.S. Pat. No. 3,182,623. A disadvantage of such a system is that propulsors (electric motors and impellers) occupy almost the entire interior of the tail section. Additionally, traditional shaftless electric motors are either too small to effectively move a vessel or, if large enough, add significant weight to the vessel.
An improved marine propulsor has been disclosed in U.S. Pat. No. 5,078,628, incorporated herein by reference. The propulsor consists of a shaftless motor with disk-shaped rotor and stators mounted in the vessel structure with a blade hub mounted on the rotor. The hub includes propeller blades extending beyond the circumference of the vessel housing.
In manufacturing this improved propulsor, problems have been encountered in centering the rotor. It is difficult to achieve the proper gaps between the stators and the rotor and the proper bearing clearance at an intermediate stage of assembly. After final assembly, it is impossible to gain access to the bearing components in a conventional bearing assembly, thereby precluding the adjustment of the stator-to-rotor gaps and the bearing clearance at this stage. Thus, disassembly of the propulsor is required to adjust these gaps and clearances, a complicated and time-consuming prospect.
Accordingly, the objects of the present invention are to provide the following:
a) an improved rotor assembly for axial gap motors; PA0 b) an improved rotor assembly permitting the axial displacement of the rotor support assembly; PA0 c) an improved rotor assembly permitting the stator-to-rotor gaps to be adjusted after assembly; and PA0 d) an improved rotor assembly permitting the rotor bearing clearance to be adjusted without requiring the disassembly of the motor.
Other objects and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.